Centrifugal separators



June 4, 1963 I E. A. DAUBMAN 3,092,576

- CENTRIFUGAL SEPARATORS Filed Feb. 18, 1959 2 Sheets-Sheet 1 F I G I INVENTOR.

ATTORNEY June 4', 1963 E. A. DAUBMAN 3,

' CENTRIFUGAL SEPARATORS Filed Feb. 18. 1959 z Sheets-Sheet 2 FIG.3

INVENTOR.

ARD A. DAUBMAN M ATTORNEY United States Patent 3,092,576 CENTRIFUGAL SEPARATORS Edward A. Daubman, East Moline, [1]., assignor to Ametek, Inc., a corporation of Delaware Filed Feb. 18, 1959, Ser. No. 794,159 2 Claims. (Cl. 210-146) The present invention relates to centrifugal separators, and particularly to a new and improved cover interlock mechanism that will prevent access to the interior of the separator while the same is operating.

A principal object of this invention is to provide a cover interlocking mechanism, effective during the accelerating and decelerating of the rotatable basket of a centrifugal separator that is driven and braked by bydraulic components in a closed hydraulic circuit.

Another object of the invention is to provide a cover interlock mechanism for a centrifugal separator that will require manual restarting of the main motor each time the cover is opened.

One aspect of the invention may be to provide a centrifugal separator with a closed circuit hydraulic system embodying an hydraulic pump that is driven by an electric motor and wherein the hydraulic pump supplies liquid under pressure in a closed circuit to an hydraulic motor that is belted or otherwise drivingly connected to the rotatable basket of the separator. A hinged cover plate may provide access to the interior of the separator and a limit switch may be provided that is connected in series with the electric motor that drives the hydraulic pump. The hydraulic pump may be of the variable displacement type incorporating hydraulic braking for decelerating the rotatable basket of the separator. An hydraulically actuated piston and cylinder mechanism may be provided for locking the cover plate during the accelerating, running and decelerating periods of activity of the separator.

The interlock actuating mechanism may comprise a multi-piston arrangement that may be rendered effective by the application of differential hydraulic pressures applied thereto from either side of the closed circuit including the hydraulic pump and motor units. Resilient means may be provided for positively retracting the interlock for the cover when no differential hydraulic pressure is applied to the multi-piston arrangement.

The above, other objects and novel features of the invention will become apparent from the following specification and accompanying drawings which are merely exemplary.

In the drawings:

FIG. 1 is an elevational view of a centrifugal separator to which the principles of the invention have been applied;

FIG. 2 is a top plan view of the separator shown in FIG. 1; and

FIG. 3 is a schematic wiring diagram and hydraulic circuit of certain components of the invention.

Referring to the drawings, and particularly to FIGS. 1 and 2, the principles of the invention are shown as applied to a centrifugal separator of the bottom discharge type, although they may with equal facility be applied to any type of centrifugal separator. The separator shown may include a bedplate on which are mounted three equally spaced pedestals 11 that include mechanism for supporting a housing 12 for limited oscillatable movement. The housing 12 may have fixed to its sides, brackets 13 that extend into the pedestals 11 to cooperate with supporting mechanism therein.

A basket may be located within the housing 12 and may comprise a perforated cylindrical member 14 for passing liquid therethrough, which liquid is collected within an annular chamber within the housing 12. The

I bottom of the basket 14 may be provided with discharge passages for gravitating solids therein out through the bottom of the housing 12.

The basket 14 may be provided with a multiple V-belt sheave (not shown) on its vertical axis of revolution that is in driving engagement with V-belts 15. The belts 15 also engage another similar sheave (not shown) on the axis of rotation of an hydraulic motor 16. The motor 16 is of the constant displacement type and includes ports 17 and 18. The ports 17 and 18 are connected to ports 19 and 20, respectively, of a variable volume hydraulic pump 21 by lines 22 and 23. The hydraulic pump 21 by means of a control may be adjusted to deliver from zero to maximum volume of liquid to the hydraulic motor 16. An

electric motor 25 may be provided for driving the pump 21 at a constant speed.

From the foregoing it is evident that adjusting the displacement of the pump 21 will cause different rates of rotation of the basket 14. The speed of the motor 16 duringthe unloading operation is approximately 50 r.p.m. The

capacity of pump 21 may be adjusted to cause the motor 16 to rotate basket 14 at a loading speed that is substantially faster than the unloading speed; and, the pump 21 may be adjusted to cause the motor 16 to rotate basket 14 at an extracting speed that is very much faster than the unloading speed. Since the electric motor 25 rotates at a constant speed and the pump 21 cannot be reversely' driven, sudden adjustment of pump 21 from an extracting speed to any lower speed will cause the motor 16 to act as a pump tending to drive the pump 21 as a motor. However, since pump 21 cannot be driven by the motor 16 acting as a pump, a braking action on the rotation of the basket 14 is provided.

The structure thus far described is substantially the same as that shown and described in application Serial No. 657,801, filed May 8, 1957, now Patent No. 3,038,61 l, in the names of Frank OConor et al., to which application attention is directed for details not specifically described herein.

The top of the housing 12 is adapted to be covered by a top plate 26, and a cover plate 27 of semicircular form mounted on a hinge pin 27' may cover a correspondingly shaped opening in the top plate 26 to provide access to the interior of the basket 14. A normally-closed limit switch 28 adapted to be operated by a cam 28' on the cover hinge pin 27' may be arranged so that it opens when the cover plate 27 is opened, thus preventing the starting of motor 25 when cover plate 27 is open. The cam 28' may be a finger fixed to the cover hinge that opens switch 28 when the cover plate 27 is opened. The circuitry for the limit switch 28 will be described later.

In order to prevent opening of the cover plate 27 when the basket 14 is rotating, an hydraulic interlock is provided. It may comprisea cylinder 29 (see FIG. 3) mounted on top of the plate 26 0f the housing 12 and may include a plurality of aligned piston means including a piston 30 having a rod 31 extending outwardly through one end of "the cylinder 29 and serving as an interlock adapted to be moved to a position over the edge of cover plate 27 and into a socket member 31' to prevent the opening of the cover plate 27, or retracted under the action of a compression spring 32 for permitting opening of the cover plate 27.

A bore 33 within cylinder 29 that is axially aligned with piston 30 may support, for reciprocation therein, separate pistons 34 and 35. A pressure port 36 may be provided in cylinder 29, which when subjected to a predetermined pressure from line 22 through a line 36' will force pistons 35, 34 and 30 rightwardly or forwardly,

causing rod 31 to move over the edge of the cover plate 27 and into socket 31 against the action of spring 32.

Another pressure port 37 may be provided in cylinder 29 in position to be effective on piston 34 to cause it and piston 30 to move rightwardly while maintaining piston 35 in its lefthand or rearward position when liquid is supplied to port 37 from fine 23 through a line 37' under a pressure that is in excess of the pressure of the liquid being supplied to port 36 from line 22. Of course, when liquid is supplied to port 36, the pressure of which is in excess of that supplied to port 37, pistons 35. 34 and 30 will move rightwardly or forwardly to effect the interlocking action.

With the apparatus in the condition as shown in FIG. 3, closing start push-button switch 42 energizes relay coil 43 which closes switches 44 in lines L L and L thereby energizing motor 25. and closes a normally open holding switch 45, to hold the circuit for relay coil 43 when switch 42 is released.

Energization of the motor causes rotation of the pump 21. With pump 21 set for zero delivery, the pressure in lines 23 and 22 is the system back pressure of about 125 psi. Accordingly, the pressure on each end of piston35 cancels, and the pressure on piston 34 is overcome by the strength of spring 32 maintaining piston in its retracted position. Therefore, at zero speed of rotation of the basket 14, the cover plate 27 may be opened at will; however, so opening it opens cover limit switch 28, thereby deenergizing relay coil 43, thus causing de-energization of motor 25.

During an operating cycle, adjustment of pump 21 to deliver liquid to motor 16 at a rate to rotate basket 14 at a loading. extracting or unloading speed causes a pressure to build up within line 23 that is far in excess of the back pressure in line 22 and which may vary between about 300 and i700 p.s.i., thereby forcing pistons 34 and 30 rightwardly and maintaining piston in its outward positon since the only pressure on the lefthand end of piston 35 is the back pressure in line 22 of about 125 p.s.i.

With the basket 14 rotating, adjustment of pump 21 to reduce supply liquid to motor 16 causes braking to occur. Thus. this change decreases the supply of high pressure liquid to line 23, but builds up a high pressure (300-1700 p.s.i.) in line 22 that is connected to port 36, whereupon pistons 35, 34 and 30 are forced rightwardly against the action of spring 32, effectively preventing opening of the cover plate 27.

With the basket 14 rotating at the unloading speed of approximately 50 rpm. the pressure in line 23 under certain'conditions may be below 300 p.s.i. Exerting external pressure of sufiicient magnitude on piston rod 31 at this time would assist spring 32 in forcing piston 30 backward, causing the interlock to become ineffective. Therefore, socket 31' has been added to cover plate 27 to prevent this possibility.

When the pressure in lines 22 and 23 falls below a predetermined value in the neighborhood of 125 p.s.i.,

spring 32 becomes effective to force piston 30 backwardly so that rod 31 clears cover plate 27, permitting its opening at the will of the operator.

Any accumulation of liquid within cylinder 29 between pistons 30 and 34 may be drained through a. port 38.

From the foregoing it is evident that a simple hydraulic interlock has been provided that will mechanically prevent access to the interior of a centrifugal separator during rotation of the basket while permitting access to said interior when the basket is stationary.

Although the various features of the new and improved cover interlock for centrifugal separators have been shown and described in detail to fully disclose one embodiment of the invention, it will be evident that numerous changes may be made in such details, and certain features may 'be used without others without departing from the principles of the invention.

What is claimed is:

1. In a centrifugal separator having a stationary housing within which a rotatable basket is mounted, a closed hydraulic circuit including an hydraulic pump and motor means for rotating as well as stopping the rotation of said basket; an electric motor for operating said pump and motor means; a cover plate adapted to provide access to the interior of said separator; switch means within the circuit for said electric motor for de-energizing said electric motor when said cover plate is opened; an interlocking element; a cylinder mounted on the top of said housing; inter-communicating axially aligned relatively small and large cylindrical passages within said cylinder; a piston within said relatively large cylindrical passage; a rod connected to said piston and adapted to interlock with said cover plate to prevent its opening; a pair of freely floating pistons within said relatively small passage, all of said pistons being in successive axial abutting relation when the piston in said large cylindrical passage is in retracted position; means for connecting the one side of said hydraulic pump and motor means to the end of said cylinder at a port such that a hydraulic force is applied in line with said pistons; means for connecting the opposite side of said pump and motor means to said cylinder at a port in position to act on both of the pistons in said small passage when they are in their retracted positions; and a compression spring within said large passage and acting on the piston therein tending to move it to its retracted position.

2. A centrifugal separator as claimed in claim 1, in which means mounted on said cover plate cooperates with the free end of said rod when said rod is in interlocking position to prevent an operator from assisting the action of said compression spring.

References Cited in the file of this patent UNITED STATES PATENTS 1,418,616 Boisset June 6, 1922 1,766,310 Schaum June 24, 1930 1,837,244 Watson Dec. 22, 1931 2,170,786 McElroy et a1 Aug. 22, 1939 2,235,988 Frohwitter Mar. 25, 1941 2,588,634 Johnson Mar. 11, 1952 2,780,065 Spannhake Feb. 5, 1957 2,782,598 Gatewood Feb. 26, 1957 2,993,580 OConor et al. July 25, 1961 FOREIGN PATENTS 336,851 Germany Nov. 30, 1919 1,047,121 Germany Dec. 18, 1958 

1. IN A CENTRIFUGAL SEPARATOR HAVING A STATIONARY HOUSING WITHIN WHICH A ROTATABLE BASKET IS MOUNTED, A CLOSED HYDRAULIC CIRCUIT INCLUDING AN HYDRAULIC PUMP AND MOTOR MEANS FOR ROTATING AS WELL AS STOPPING THE ROTATION OF SAID BASKET; AN ELECTRIC MOTOR FOR OPERATING SAID PUMP AND MOTOR MEANS; A COVER PLATE ADAPTED TO PROVIDE ACCESS TO THE INTERIOR OF SAID SEPARATOR; SWITCH MEANS WITHIN THE CIRCUIT FOR SAID ELECTRIC MOTOR FOR DE-ENERGIZING SAID ELECTRIC MOTOR WHEN SAID COVER PLATE IS OPENED; AN INTERLOCKING ELEMENT; A CYLINDER MOUNTED ON THE TOP OF SAID HOUSING; INTER-COMMUNICATING AXIALLY ALIGNED RELATIVELY SMALL AND LARGE CYLINDRICAL PASSAGES WITHIN SAID CYLINDER; A PISTON WITHIN SAID RELATIVELY LARGE CYLINDRICAL PASSAGE; A ROD CONNECTED TO SAID INTERLOCK WITH SAID COVER PLATE TO PREVENT ITS OPENING; A PAIR OF FREELY FLOATING PISTONS WITHIN SAID RELATIVELY SMALL PASSAGE, ALL OF SAID PISTONS BEING IN SUCCESSIVE AXIAL ABUTTING RELATION WHEN THE PISTON IN SAID LARGE CYLINDRICAL PASSAGE IS IN RETRACTED POSITION; MEANS FOR CONNECTING THE ONE SIDE OF SAID HYDAULIC PUMP AND MOTOR MEANS TO THE END OF SAID CYLINDER AT A PORT SUCH THAT A HYDRAULIC FORCE IS APPLIED IN LINE WITH SAID PISTONS; MEANS FOR CONNECTING THE OPPOSITE SIDE OF SAID PUMP AND MOTOR MEANS TO SAID CYLINDER AT A PORT IN POSITION TO ACT ON BOTH OF THE PISTONS IN SAID SMALL PASSAGE WHEN THEY ARE IN THEIR RETRACTED POSITIONS; AND A COMPRESSION SPRING WITHIN SAID LARGE PASSAGE AND ACTING ON THE PISTON THEREIN TENDING TO MOVE IT TO ITS RETRACTED POSITION. 